1. Technical Field
This invention refers to a device that helps a sewage network manager collect information about the condition of the network in order to maintain it in good operating condition.
A network needs to be cleaned periodically to get rid of deposits and other obstructing materials and to guarantee optimal flow of the water through its pipes.
The cleaning process needs to be done every 6 month to 12 years with an average periodicity of 3 years depending on the characteristics of the network.
The purpose of network monitoring is to adjust the cleaning frequency and to check the pipes for structural condition or other problems.
2. Background Art
Traditionally, man holes and pipes of big dimensions are observed directly by visiting them. For smaller pipes, the inspection can be made from the top of a visiting chamber with the help of a wired camera fitted at the lower extremity of a vertical pole put in the chamber down to the pipe inlet, and that can observe the inside of the pipe on a limited length.
This kind of inspection is more or less complete, and more or less difficult to implement whether it is realized directly without preparing the pipe or after draining and cleaning it.
Another usual method is to insert a wired camera mounted on a remote control wheeled cart that moves inside the pipe after the latter has been drained and cleaned.
The drawbacks of these methods are that they involve, depending on the situation:                The presence of a person inside a confined environment with hygiene risk and exposure to dangerous gas like H2S,        The continuous presence of a complete team including someone able to interpret the observation, such a team being generally mobilized during day time when the sewage flow is maximum.        A low ratio of distance of piping observed over time spent and means deployed.        A necessity to cut or limit the water flow in the pipe which then cannot accomplish its primary function during the observation or that has to be by-passed by an alternate system to be installed,        A relatively regular bottom surface of the pipe without big obstacles or differences in level for the cart to be able to progress smoothly,        Expensive equipment that are limited in number and cannot be used in situations where there is a risk of damage or loss.        The opening of many chambers for access, display and ventilation and thus causing odours, safety and circulation problems for the neighbourhood,        Limited distance between visiting chambers to allow observation of the whole piping section.        
The following patents are related to the art.
Patent DE 4114601 describes a wheeled inspection unit moved along inside the sewage pipes and connected to a control and evaluation unit at least partially without.
Patent DE 4208863 describes an arrangement which has a transport mechanism with a signal generator and receiver. The signal generator is in the form of a microwave generator which produces synthetic pulses.
Patent EP 1749944 describes an inspection device which has compressed air supply for cleaning of water when positioning the pressure-tight housing at the channel wall. A waterproof camera unit is provided for taking pictures of the channel wall in the housing.
Patent DE29900544 which describes a device that transmits visual information of a sewer pipe to a display unit at the surface. The device consists of a housing in which a camera and lights linked by wire to a display unit at the surface and a nozzle used to push the device inside the pipe.
Patent DE9320538 describes a wheeled housing in which a camera, a location sensor and a storage unit are fitted, used to record visual and location information in a pipe and to deliver them afterwards to a processing and visualization unit at the surface.
Patent DE20 2006 016 642 describes a floating housing on which is fitted a camera and a lighting system and is held on one side by an electrical wire (to transmit signals and to exert a pulling or retaining action) and pulled on the other side by cleaning nozzles normally used for cleaning sewer piping.